Currently I run a convert job on my nwsp2 with the released firmware version 17.0
As the disk is big (3TB) I need to wait several hours to see what happens on nas rebooting
With a nswp2, your issue is amazing as the boot script does not update/delete shares/user accounts according the disks found (eg required for 5/2 bigx)
So the shares would not have to disappear :scratch